Essay On Nervous System – Structure/Outline
- Evolution and Development of the Nervous System
- Types of Nervous System
- Structure and Parts of the Nervous System
- The function of the Nervous System
- Disorders of the Nervous System
The nervous system is a critical and complex part of the human body. It enables senses such as touch, sight, hearing, and taste to work properly, and even helps us respond to changing or stressful situations.
Every day, our brain receives signals and sends messages all over the body to help us interact with the world around us. Our nerves are made up of a vast network of cells that allow us to register external factors like temperature and pressure,
as well as complex internal information such as memories and emotions. With the help of our nervous system, we can adapt quickly to changes in our environment, both mentally and physically.
Evolution and Development of the Nervous System
The nervous system has evolved over the centuries. In primitive organisms, the nervous system had very simple structures and functions; however, with time, these structures became more complex.
The first signs of an organized nervous system occurred in invertebrates such as Cnidaria and Molluscs, which developed a nerve net. These networks are formed by interconnecting neurons and help organisms sense the environment. As vertebrates evolved, a central nervous system was eventually formed, which consists of two parts: the brain and the spinal cord.
Types of Nervous System
The human nervous system can be divided into two major systems-the central nervous system (CNS) and the peripheral nervous system (PNS). The CNS is composed of the brain and spinal cord, while the PNS consists of all other nerves that connect to other parts of the body. The PNS includes both sensory and motor neurons, as well as autonomic nerve fibers that control involuntary functions such as heart rate and respiration.
(1) Central Nervous System (CNS):
The CNS is the brain and spinal cord, which are housed inside the skull and vertebral column. This system is responsible for controlling a wide variety of functions, from voluntary movement to complex cognitive processes such as decision-making.
(2) Peripheral Nervous System (PNS):
The PNS consists of 12 pairs of cranial nerves that originate from the brain and 31 pairs of spinal nerves that come from the spinal cord. These nerves regulate both voluntary and involuntary functions in the body, such as breathing, movement, sensation, and digestion.
Structure and Parts of the Nervous System
The human nervous system is composed of billions of neurons that are connected by synapses. The main parts of the nervous system include:
Central Nervous System (CNS):
It consists of the brain and spinal cord.
The brain acts as the control center for all activities, including sensory, motor, and cognitive functions. It is composed of billions of neurons that are connected by synapses. The four major divisions of the brain include the cerebrum, the cerebellum, the thalamus, and the hypothalamus.
(b) Spinal Cord:
The spinal cord is a long, thin bundle of nerves that runs down the center of the back. It is responsible for the transmission of sensory and motor signals between the brain and other parts of the body. It also contains nuclei that are involved in reflexes and other autonomic functions.
Peripheral Nervous System (PNS):
Contains 12 pairs of cranial nerves and 31 pairs of spinal nerves.
Cells that make up the nervous system are responsible for sensing, processing, and transmitting signals throughout the body.
Junctions between neurons allow communication between them.
Chemicals released by neurons carry signals to other neurons.
(d) Glial Cells:
Supportive cells in the nervous system provide insulation and protection for neurons.
The Function of the Nervous System
The nervous system has many functions, including sensing stimuli from the environment, processing information, and controlling behavior. It is also responsible for regulating physiological processes such as breathing, digestion, heart rate, and blood pressure.
The nervous system is involved in coordinating complex behaviors such as walking or speaking. In addition to these functions, the nervous system helps us adapt to changing environments, learn new skills, and remember important information.
The nervous system is also responsible for the production of hormones, which act as chemical messengers that help regulate body functions. Finally, the nervous system works in conjunction with other systems in the body such as the endocrine and immune systems to keep us healthy.
Disorders of the Nervous System
The nervous system can be affected by a variety of disorders, such as:
(a) Neural Tube Defects:
These are birth defects that affect the development of the brain and spinal cord. They can cause physical disabilities, learning disabilities, and even death in severe cases.
(b) Traumatic Brain Injury (TBI):
This is caused by a sudden trauma to the head, such as a fall or car accident. It can result in physical and cognitive impairments, such as memory loss or impaired motor skills.
This occurs when the blood supply to part of the brain is interrupted, resulting in damage to the affected area. It can cause paralysis, difficulty speaking or understanding language, and other cognitive impairments.
(d) Parkinson’s Disease:
This is a neurological disorder that affects movement. It is caused by the loss of brain cells that produce dopamine, which is responsible for controlling muscle movements. Symptoms include tremors, stiffness, and impaired balance and coordination.
(e) Multiple Sclerosis (MS):
This is an autoimmune disorder that affects the brain and spinal cord. It causes damage to the myelin sheath, which is a protective coating around neurons. Symptoms include vision problems, balance issues, fatigue, and muscle weakness.
(d) Alzheimer’s Disease:
This is a type of dementia that affects memory, thinking, and behavior. It is caused by the death of nerve cells in the brain. Symptoms include memory loss, confusion, changes in personality, and difficulty with daily activities.
This is a disorder characterized by seizures that are caused by abnormal electrical activity in the brain. Seizures can be mild or severe and can cause physical symptoms such as convulsions or loss of consciousness.
(f) Autism Spectrum Disorder (ASD):
This is a neurological disorder characterized by difficulties with social interaction, communication, and behavior. Symptoms usually begin during early childhood and can range from mild to severe.
What are the types of peripheral nervous systems?
The peripheral nervous system is divided into the somatic and autonomic nervous systems. The somatic nervous system controls voluntary movement, such as walking, talking, and grasping objects. The autonomic nervous system controls unconscious processes such as heart rate, digestion, and breathing.
What are the functions of the central nervous system?
The central nervous system is responsible for processing and integrating sensory information, controlling movement, regulating emotions, and coordinating complex behaviors. It is composed of the brain and spinal cord.
What is the largest nerve in the body?
The sciatic nerve is the largest and longest nerve in the body. It extends from the lower back down to the feet and controls movement of the lower limbs, as well as providing sensation in the legs and feet.
What are some common disorders of the nervous system?
Some common disorders of the nervous system include neural tube defects, traumatic brain injury, stroke, Parkinson’s disease, multiple sclerosis, Alzheimer’s disease, epilepsy, and an autism spectrum disorder.
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